Magnetic Properties of Hematite Nanotubes Elaborated by Electrospinning Process

Hematite nanotubes are successfully prepared using an electrospinning technique and studied by superconducting quantum interference device magnetometry. At room temperature, the hysteresis properties observed are strongly controlled by the size of the nanofibers. The coercivity force increases with the average diameter while the remnant magnetization decreases. The moment versus temperature data for samples with different nanotubes' average diameter show two magnetic transitions assigned to Morin transitions. The origin of this phenomenon is traced to the presence of very thin nanotubes responsible for an additional Morin transition at low temperature. As a consequence, and based on previous works, a phenomenological description of the influence of hematite nanostructures size on the Morin temperature is proposed for the first time.